Pressurized containers, comprising, for example, enclosed environments that require ingress and egress, are often closed and sealed by means of a cover or hatch that is hingedly mounted upon suitable support structure of the container or environment enclosure, and is latched upon and seals against; an external surface structure of the container or enclosure. Such a cover or hatch is known as a "pressure-assist opened" type closure since the sealing force tends to decrease as the pressure within the container or enclosure is increased, or considered from another viewpoint, the internal pressure of the container or enclosure tends to open or "assist" the opening of the hatch or cover. In connection with such a "pressure-assist opened" cover or hatch, should the latch or hinge mechanism experience failure, the cover or hatch will be forced open thereby permitting the pressurized environment within the container or enclosure to escape. This is obviously an undesirable situation, and with respect to particular applications or environments in connection with which such pressure-assist opened covers or hatches could be utilized, but where, for example, it is absolutely critical that the pressurized environment within the container or enclosure be maintained or preserved, the disposition, operation, seating, and sealing of such pressure-assist opened covers or hatches prohibits their use within such applications or environments.
As an alternative to the aforenoted pressure-assist opened covers or hatches, some laboratory containers or enclosures employ an oval-shaped cover or hatch that is able to be installed upon and disposed internally within the container or enclosure as a result of the smaller axis of the oval-shaped cover being initially disposed parallel to the longer axis of a smaller, similarly configured oval-shaped opening formed within the container or enclosure, inserting the cover or hatch end-wise through the opening of the container or enclosure, and then aligning the oval-shaped cover or hatch with the oval-shaped opening of the container or enclosure such that the cover or hatch seats upon and seals against internal surface structure of the container or enclosure when the interior of the container or enclosure is subsequently pressurized. This type of cover or hatch closure is known as a "pressure-assist closed" type closure since increases in the internal pressure of the container or enclosure tend to further increase the sealing force due to the fact that the internal pressure within the container or enclosure tends to close or "assist" the closing of the hatch or cover closure.
It is therefore readily appreciated that this type of cover or hatch closure will not experience a normal or credible failure resulting in the closure being opened under pressurized conditions since the relatively larger oval-shaped cover or hatch closure cannot physically pass through the relatively smaller oval-shaped container or enclosure opening while the closure is disposed in its normal disposition or orientation with respect to the container or enclosure opening. The only way that the cover or hatch closure can be removed externally of the enclosure or container when the cover or hatch closure is disposed in its normal disposition or orientation with respect to the container or enclosure opening is by reducing the internal pressure within the container or enclosure and physically moving the cover or hatch closure with respect to the container or enclosure in a manner which is in effect the reverse of that of the cover or hatch closure installation procedure. It is therefore further appreciated that the operative characteristics of such a pressure-assist closed type closure wherein such a closure cannot or will not experience or exhibit a normal or credible failure mode renders such pressure-assist closed type closures the preferred closures or closures of choice in connection with pressurized containers requiring high reliability performance characteristics. An operative drawback, however, of such pressure-assist closed closures is the compound motion or movement necessarily required in order to position or orient the closure internally through the container or enclosure opening and within the container or enclosure, as well as the logistical space required for permitting the closure to undergo such compound motion or movements.
Aircraft doors conventionally comprise similar pressure-assist closed closures, however, in order to eliminate the requirement for the aforenoted compound motion or movement, the doors are provided with a door width which is greater than the width of the aircraft frame opening while the door height is slightly less than the aircraft frame opening height. Such structure enables the doors to be opened and closed in accordance with a more simplified technique or movement wherein, for example, a door that was opened to the outside of the aircraft, can be swung inwardly of the aircraft while the door is turned sideways, the door is then rotated or pivoted about a vertical axis so as to in effect dispose the door substantially parallel to the aircraft wall within which the aircraft frame opening is provided, and the door is then moved in an outward direction such that the door seats upon interior frame structure of the aircraft frame opening and uses an inflatable seal structure to seal between the door and the interior frame structure of the aircraft frame opening. While such system is substantially more simplified than the aforenoted closures requiring the compound motions or movements, a significant amount of space is nevertheless still required inside the aircraft so as to accommodate or facilitate the closure motion or movement.
Space suits obviously require highly reliable closures since the failure of the closure seal could endanger the life of the astronaut. However, due to the extremely limited amount of space which is available internally within the space suit, the use of conventional pressure-assist closed closures is not viable, and accordingly, such closures have not been employed upon present state-of-the-art space suits. As has been noted hereinbefore, the employment or utilization of presently available pressure-assist closed closures requires the intrusion of the closure into the interior of the space suit prior to reorientation of the closure with respect to the opening framework of the suit so as to properly align, seat, and seal the complementary sealing surfaces or structures of the suit framework and the closure, and such procedures require an inordinate or excessive amount of interior space. In addition, the complex motion or movement necessary to properly reorient the closure with respect to the suit framework is difficult to automate, is difficult to achieve if being manually performed by the astronaut, and is particularly difficult to achieve when the closure is being manually manipulated by the astronaut if the suit is provided with a rear entry closure since the astronaut cannot easily see the closure and cannot readily perform the complex alignment motion or movement of the closure with respect to the suit framework opening which is located behind the astronaut's head or back.
A need therefore exists in the art for a new and improved pressure-assist closed closure which can be utilized upon any pressurized container or environment enclosure, which is particularly adapted for use upon an astronaut's space suit, especially with respect to a space suit provided with a rear entry closure, and which is relatively easy to manually manipulate without requiring an inordinate or excessive amount of internal space within the container, enclosure, or suit in order to properly position and orient the closure with respect to the container, enclosure, or suit when it is desired to unseal and open, or close and seal, the container, enclosure, or suit frame opening in connection with which the closure is employed so as to unseal or seal the container, enclosure, or suit under depressurized or pressurized conditions.